The irony is rich. The term "snake oil" has come to mean everything that is fraudulent. The reference is to the infamous "snake oil salesman" who pitched and sold his wares out of the back of a wagon to the unsuspecting villagers of the American west.

Snake oil has real medicinal value. It was used as medicine before the North American continent was on the map. Centuries ago the Chinese used an oil made from a cold water snake called Enhydris chinensis to treat joint pain and bursitis. It was introduced to the US by Chinese laborers who worked on the Transcontinental Railroad in the mid 1800's. There's evidence that the ancient Egyptians used it too. In the early 1700's the English had a patent medicine made from snake oil. Snake oil was sold here as a panacea in the early 1900's, but the products sold were probably more filler and adulterant than they were actual snake oil.

So what's in it that's good for you? Snake oil, depending on the snakes used to derive it, can be a rich source of an fatty acid known as EPA, eicosapentanoic acid. EPA is used by the body to synthesize series 3 prostaglandins, which are anti-inflammatory and pain relieving. You can know EPA is important because it's in human breast milk. EPA is effective for treating depression, improving cognitive function, autoimmune diseases including rheumatism, high cholesterol, hypertension, and more.

EPA can be derived in the body from other fatty acids, but it's much easier to eat in your food. The richest sources are fish: herring, mackerel, salmon, trout, pilchards, menhaden and sardines. Fish do not make their own EPA. They get it from eating algae like spirulina, which we also can eat. Plant foods don't contain any EPA at all.

Part of the reason it's easier to eat EPA than to make it in your body has to do with human genetics. Some people have the gene to make the enzyme which lets them convert ALA (alpha linolenic acid) into EPA. Other people have mutations in their genes that limit their ability to do the conversion. Diabetes and some allergies also limit a person's ability to convert ALA to EPA. ALA is an essential fatty acid, meaning that no humans can make it; we have to get it from the diet.

If we don't make it very well, and we don't eat much fish, we need to get our EPA some other way to keep our cell membranes happy. Many healthcare professionals recommend that we take fish oil. Fish oil contains 12-18% EPA. Salmon oil tops the list at ~18%. Chinese water snake oil contains ~ 20% EPA, whereas rattlesnake oil is said to contain 8.5%. Cod liver oil has more DHA than EPA and is best reserved for specific uses, like building baby brains or healing brain injuries.

The reason why some snakes have more EPA than others has to do with the temperatures that they live in. Snakes and fish are both cold blooded, so they have to function with their bodies at the same temperature as their environments. Omega 3 fats like EPA don't harden in cold temperatures like omega 6s do. They help keep cell membranes flexible. Flexible membranes don't get injured as easily, and are able to function better. Cold water fish, or cold water snakes, will have more EPA than those that live in warm sunshine, like rattlesnakes.

The next time someone tells you that a treatment is "snake oil", remember this. Public attitudes and language reflect our history, not our future. Science continues to give us reason to revise belief systems, erase myths, and sometimes to welcome old treatments back into the fold.

As the winter progresses into darkness and cold, every little thing that makes me happy gets celebrated. One thing that makes me really happy is delicious sushi. I am grateful that Sho Japanese Cuisine is right across the street from my office. They have tasty fish and excellent sake.

There's a debate raging about fish---whether or not we should eat it, what kind, and what we should do about the toxic mercury that contaminates much of the world's fish supply. There are some who say don't worry about it, fish is so good for you that you should just eat it and don't worry about the mercury. There are others who say that fish is so dangerous that you shouldn't eat any, and that you should supplement fish oil that has been tested and is free of mercury instead. There is no doubt that most Americans don't get enough omega 3 fatty acids, and that we can get them from eating more fish. So where do I fall? Somewhere in the middle. Because really, like all diet and lifestyle choices, it is a personal decision.

For the last century fish have carried increasing levels of mercury and other contaminants. Carnivorous fish have more, because many toxins bio-accumulate. Equatorial fish have more, because there are more people and hence more pollution around the midsection of the planet. Interestingly, since the economy took a dive a few years back, the mercury levels in fish have declined. Some say that it is because there is less coal being burned in China. Most environmental mercury comes from coal smog. All this is debatable, but the fact that there is mercury in fish, and that mercury is bad for people, especially people's brains, is very well documented.

So what do I do? I eat fish 1-2 times a week, and supplement fish oil, ideally every day, though I often fall short of that goal. I choose fish that are less likely to have a high mercury load---less carnivorous fish, smaller fish, more northern fish, instead of tuna from near the equator. I supplement zinc, because being replete for good metals reduces one's absorption of bad metals when introduced. And I support my liver's detoxification mechanisms in many ways, not the least of which is eating sulfur rich foods like cilantro and garlic. I don't know exactly what balance will be right for you, but it is worth being conscious of the toxic challenges that may be in your food, and acting intentionally about it.

Edit 11/28/11: I just heard that fish have high enough selenium levels to bind up most of the mercury that they ingest, and possible render the majority of it non-absorbable to us. I have not confirmed this yet, but it brings up the question: would repletion for selenium benefit humans with regard to avoiding mercury toxicity? I do know that most humans are deficient in selenium. And I also know that selenium is a key cofactor in the activation of thyroid hormone; if you don't have enough selenium, you will feel tired. So it's worth considering both selenium and zinc as nutrients to bulk up on if you want to eat fish. More updates as I learn more!